Hydrocracking process with stabilized y-zeolite catalysts

ABSTRACT

Highly active, hydrothermally stable and ammonia-stable Y zeolite compositions are disclosed, which compositions are useful as adsorbents, hydrocarbon conversion catalysts, and as acidic supports for catalytic metals. The stabilized Y zeolite composition is prepared from a sodium Y zeolite by a novel sequence of: (1) partial exchange of ammonium ions for sodium ions, (2) steam calcination under controlled conditions of time, temperature and steam partial pressure, and (3) further ion exchange of ammonium ions for sodium ions to reduce the final Na2O content to below about one weight-percent.

United States Patent 1191 1111 3,897,327 Ward 3/ *July 29, 1975 [54]HYDROCRACKING PROCESS WITH 3,507,812 4/1970 Smith et al. 252/455 ZSTABILIZED Y ZEOLITE CATALYSTS 3,766,056 l0/l973 208/] l l 3,781,19912/1973 208/111 [75] Inventor: John W. Ward, Yorba Lmda, Calif. 3 793132 2/ 974 20 3,835,028 9/1974 208/] ll [73] Assgnee' 3,849,293 11/1974Ward 208/111 Los Angeles, Cal1f.

[ Notice: The portion of the term of this Primary ExaminerDelbert E.Gantz patent subsequent to Dec. 25, 1990, Assistant Examiner-James W.Hellwege has been disclaimed. A trorney. Agent. or Firm- Lannas S.Henderson; [22] Filed Oct 15 1973 Richard C. Hartman; Dean Sandford [21]Appl. No.: 406,683 [57] ABSTRACT R l t d US, A li ti D t Highly active,hydrothermally stable and ammonia- [63] continuatiommpan of sen NOS. 9]123 Oct 20 stable Y zeolite compositions are disclosed, which 1971,abandoned, and Sen 236J'85, March compositions are useful as adsorbents,hydrocarbon 1972,9 3,731,199 conversion catalysts, and as acidicsupports for catalytic metals. The stabilized Y zeolite composition is[52 vs. (:1. 208/111; 252/455 2 p p from a sodium Y Zeolite by a novelSequence [51] Int. Cl C10g 13/02 partial x hange of ammonium ions forsodium [58] Field of Search 208/111; 252/455 2 ions, Steam n i n n r onrolled conditions of time, temperature and steam partial pressure, [56]Refe Cit d and (3) further ion exchange of ammonium ions for UNITEDSTATES PATENTS sodium ions to reduce the final Na O content to below3,449,070 6/1969 McDaniel et al.... 252/455 2 about one welght'percem3,457,191 7/1969 Erickson et a]. 252/455 Z 16 Claims, 2 Drawing FiguresPATENTED JUL 2 9 I975 SHEET w MN; 33 t2:

3 3 N9 3 a 3 E N 3 3 3 3 fix 3 3 Q I 2 G23 mEZSE k0 s3 22 Q2 55 2w 0 12Q2 EEG O I 3 EEG o2 Sm 2 U E 02 m 535w 4 9m 10 $525 3 50 9:55 ZQEEGEU:55: 3 l 3 l 3 l 3 I 3 l 3 01 lg? I-IYDROCRACKING PROCESS WITHSTABILIZED Y-ZEOLITE CATALYSTS RELATED APPLICATIONS This application isa continuation-in-part of Ser. No. 191,123, filed Oct. 20, 1971, nowabandoned, and Ser. No. 236,185, filed Mar. 20, 1972, now US. Pat. No.

BACKGROUND AND SUMMARY OF INVENTION In acid-catalyzed hydrocarbonconversions, the use of catalysts based on various forms of Y zeolitehas become widespread. For such purposes, the most desirable forms of Yzeolite are those wherein the original zeolitic sodium ions have beenreplaced by less basic cations such as hydrogen ions, or polyvalentmetal ions such as magnesium or rare earth metal ions. Still anotherdesirable form is sometimes referred to in the literature as thedecationized form, which it now appears may actually consist of a formin which part of the exchange sites are actually cation deficient and inwhich another portion is satisfied by hydrogen ions. To produce thehydrogen and/or decationized forms, the general procedure is to exchangemost or all of the original sodium ions with ammonium ions, and theresulting ammonium zeolite is then heated to decompose the zeoliticammonium ions, first forming a hydrogen zeolite, which may upon furtherheating be at least partially converted by dehydroxylation to the trulydecationized form. The hydrogen form, the decationized form, and themixed hydrogen-decationized forms will be referred to hereinaftercollectively as metal cation deficient" Y zeolites.

A problem which was encountered at an early stage in the development ofY zeolite catalysts was that of thermal and hydrothermal stability. Themetal-catiom deficient zeolites were found to be in general more activethan the polyvalent metal forms, but did not display the hydrothermalstability of the latter. Hydrothermal stability refers to the ability tomaintain crystallinity and surface area upon calcination after exposureto water vapor, or upon exposure to water vapor at high temperatures.Severe hydrothermal conditions are often encountered in hydrocarbonconversion processes, either as a result of inadvertent process upsets,or during oxidative regeneration of the catalysts, or in other ways. Forthese and other reasons most commercial processes such as cracking orhydrocracking utilize a polyvalent metal-stabilized form of the zeolite,even though some degree of activity is thereby sacrificed.

In recent years however this picture has changed somewhat. Several formsof stabilized metal-cationdeficient Y zeolites appear to be available,or at least described in the literature. A common feature involved inthe manufacture of such stabilized zeolites appears to be a calciningstep, in which an ammonium form of the zeolite is calcined at arelatively high temperature, usually above about l000F, either in thepresence or absence of added steam. This calcination appears to bringabout in varying degrees a removal of lattice alumina from the anioniccrystal structure, with a resultant shrinkage in the unit cell size tovalues ranging between about 24.2 and 24.2 A. Exemplary disclosures ofsuch procedures can be found in US. Pat. Nos. 3,293,192 to Maher et a1,3,449,070 to McDaniel et al., 3,354,077 to Hansford, 3,493,519 to Kerret al., 3,513,108 to Kerr, and 3,506,400 to Eberly et a1. Myinvestigations have shown that while the procedures described in each ofthe foregoing patents are capable of producing a metaLcation-deficient Yzeolite of improved hydrothermal stability, none of such proceduresresult in a product having the optimum combination of activity,hydrothermal stability, and ammonia stability of the zeolites producedherein.

It should be noted that ammonia stability is in many cases as importantas hydrothermal stability. In cracking and hydrocracking processes, thefeedstocks often contain substantial quantities of nitrogen compoundswhich are largely converted to ammonia. These nitrogen compounds, aswell as the ammonia, not only suppress catalytic activity in varyingdegrees, but in many cases, especially when water is also present, tendto destroy surface area and crystallinity of the best steamstabilized Yzeolite catalysts of the prior art. Ammonia stability is also essentialin catalysts which may, after partial deactivation by metalagglomeration, be subjected to the aqueous ammonia rejuvenationprocedure described in US. Pat. No. 3,692,692. The ability of thestabilized zeolites described herein to withstand the combineddestructive effects of water and ammonia in contrast to othersteam-stabilized Y zeolites has not yet been explained.

Briefly summarizing, the critical steps in the manufacture of thestabilized zeolites of my invention are as follows:

1. The initial sodium Y zeolite is subjected to a preliminary ammoniumion exchange to replace most, but not all, of the zeolitic sodium withammonium ions.

2. The resulting ammoniumsodium zeolite is then calcined in the presenceof steam under controlled conditions of time, temperature and steampartial pressure correlated to reduce the unit cell size of the zeoliteto between about 24.40 and 24.64 A.

3. The steam-calcined zeolite is then re-exchanged with ammonium salt toreplace at least 25 percent, and preferably at" least about percent, ofthe remaining sodium with ammonium ions.

The chemical and/or physical changes which take place during step (2) ofthe foregoing procedure appear to be primarily responsible for theunique ammonia stability of the final product. As noted above, the unitcell shrinkage which occurs during this step is believed to involvedealumination of the anionic crystal structure. It now appears howeverthat different types of dealumination can take place during thiscalcination step, depending upon the sodium content of the zeolite fromstep (1), the steam partial pressure in step (2), and perhaps otherfactors. Certain thermally and/or hydrothermally stabilized Y zeolitesof the prior art, even though displaying a unit cell constant within theranges produced in step (2) herein, have been found to display markedlyinferior stability to ammonia. The ammoniastable compositions of thisinvention hence appear to be the result of achieving the necessary unitcell shrinkage under the proper conditions, principally sufficient steamatmosphere and a sufficient residual sodium content in the zeolite. Agiven unit cell shrinkage obtained in a substantially dry atmosphere, orin the substantial absence of zeolitic sodium results in much inferiorproducts as compared to a product of the same unit cell constantproduced in the presence of steam and zeolitic sodium ions. It wouldhence appear that different types of dealumination take place, perhapsat different sites of the anionic crystal structure, depending upon suchfactors as hydration and cationic influences.

To illustrate the foregoing, US. Pat. No. 3,449,070 to McDaniel et aldiscloses a thermal stabilization treatment which apparently is carriedout under a'nhydrojus' conditions to produce a hydrothermally stableproduct having a unit cell size of from 24.40 to 24.55 A., which ismostly within the range produced herein. However, these products havebeen found to display poor ammonia stability. Also, US. Pat. No.3,493,519 to Kerr et al. discloses a stabilization'treatment wherein anapparently sodium-freearnmonium Y zeolite is calcined in the presence ofsteam. This product likewise, though hydrothermally stable, has beenfound to display inferior am'monia' 'fstability, The ultrastable Yzeolite compositions prepared by the method of Us. Pat. No. 3,293,192have been found to be completely unstable to ammonia, due apparently toexcessive unit cell shrinkage, as well as a possible dificiency inzeolitic sodium and/or steam during the final calcination treatment.Finally, US. Pat. No. 3,354,077 to Hansford discloses a steamstabilization treatment under conditions of time, temperature, steampressure and zeolitic sodium content which overlap the criticalcombination of those conditions required herein, but there is no teaching of an ammonia-stable product, or of the critical combination ofconditions required to produce such a product. Hansford likewise failsto disclose the final ion exchange step required herein.

In addition to high stability, the zeolites of this invention alsodisplay unusually high catalytic activity for acid-catalyzed reactionssuch as cracking, hydrocracking, isomerization, etc, as compared to thestabilized zeolites of the prior art. This is believed to be dueprimarily to the fact that thermal stabilization in the presence of bothsteam and sodium ions brings about a higher degree of stabilization fora given degree of unit cell shrinkage than is achieved in the absence ofsteam, or in the absence of sodium ions. The dealumination of theanionic crystal structure which occurs during stabilization, and whichapparently brings about unit cell shrinkage, also results in thedestruction of catalytically active ion-exchange sites. It is thereforedesirable to effect a maximum of stabilization with a minimum ofdealumination, or unit cell shrinkage. The process of the presentinvention achieves this objective to a substantially greater degree thanprior art methods.

From the foregoing, it will be apparent that there are criticallimitations upon each of the major steps of my process, and that theselimitations are cooperatively interrelated with each other in suchmanner as to produce a final product which is not only hydrothermallystable and ammonia stable, but highly active. To the best of myknowledge, none of the stabilization treatments described in the priorart teach methods for achieving this optimum combination of properties.

For purposes of this invention, a hydrothermally stable zeolite isdefined as one which retains at least about 70 percent of itscrystallinity after rehydration and calcination for one hour at 900F. Anammonia-stable zeolite is defined as one which retains at least about 60percent of its crystallinity after being subjected to the ammoniastability test hereinafter described.

DETAILED DESCRIPTION The initial sodium Y zeolite starting materialutilized 'h'erein ordinarily has a sio2/A12o3mo1e ratio between about 3and 6, and contains about 10 14 weightpercent of sodium as Na O. In theinitial ammonium ion exchange step, the sodium .zeolite is digested inconventional manner with an aqueous" solution of a suitable ammoniumsalt such as the chloride, nitrate, sulfate, carbonate, acetate, etc, toreplace at least 20 percent, preferably at least about 50 percent butnot more than about percent, of the original sodium ions with ammoniumions. The sodium content shouldbe reduced to about 0.6 5 percent,preferably about l 4 percent by weight as Na O. At this point the unitcell size of the zeolite is greater than 24.64 A., usually between about24.65 and 24.75A.

Following the initial exchange treatmen t,-' l have found that in orderto produce a composition having the desired properties outlined above,itis essential that the ammonium-sodium zeolite at this'stagebe calcinedin the presence of steam, as opposed to calcination under anhydrousconditions. As noted above,"both high temperatures and a substantialpartial pressure of steam are necessary in order to achieve the desiredhydrothermal and ammoniastability via dealumination and unit cellshrinkage. The steam treatment also alters the pore size distribution ofthe zeolite; the initial Y zeolite has uniform pore diameters of about10-12 A., while in the steamed product a substantial proportion of thepore volume is in pores of greater than 20 A. diameter.

For effective stabilization, the calcination should be carried out whilemaintaining at least about 0.2 psi water vapor pressure, preferablyabout 2 4 15 psi, and still more preferably about 5 15 psi, for asubstantial time at temperatures above 600F. This objective can berealized by any procedure capable of maintaining the desired water vaporpartial pressure in contact with the zeolite during at least asubstantial portion of the heating. In one modification, the wet zeolitefrom the exchange step can merely be heated in a covered container so asto retain the water vapor generated therefrom. Alternatively, thezeolite can be introduced into a batch or continuous rotary furnace, ora static bed calcination zone, into which preheated steam or humidifiedair is introduced. Still another alternative is to heat the wet zeolite,with or without added water, in an autoclave equipped with a pressurerelief valve such that super-atmospheric pressures of steam can bemaintained therein.

Operative steaming temperatures range between about 600 and 1650F,preferably between about 800 and 1650F. In any case, the factors oftime, temperature and steam partial pressure should be correlated so asto effect the desired stabilization, yet avoid substantial degradationof the crystal structure. The duration of treatment is usually at leastabout 0.5 minutes, preferably about lOminutes to about 4 hours, andstill more preferably about 0.5 4 hours, but in any event is sufficientto reduce the unit'c'e'll sizeto between about 24.40 and 24.64 A.,preferably between about 24.42 and 24.62 A. This reduction in unitcell'size is a convenient indicia of the degree of stabilizationobtained. g I I I The steam calcined zeolite is then reexchang ed withammonium salt solution under sufficiently seyere conditions to reducetheremaining zeoliti'c sodium content of the zeolite tofless than 2,preferablyless'ithan about 1 and still more preferably less than about0J6weightpercent, as Na O. This ordinarily involves replacing at least25 percent, preferably at least about 70 percent, of the remainingzeolitic sodium with ammonium ions.

It should be realized that this second exchange step a does notintroduce any appreciable amount of ammonium ions into the exchangesites which were dehydroxylated in the previous steam calcination step;nearly all of the ammonium ions which go into the zeolite at this pointdo so by replacing remaining sodium ions. Since for catalytic purposes asubstantial ammonium zeolite moiety is desired in the final product forconversion to catalytically active sites of Bronsted acidity, it will beapparent that sufficient sodium should be initially present at thesecond exchange step, and sufficient of this remaining sodium should beexchanged out with ammonium ion, to provide the ultimately desiredBronsted acidity. For this purpose, the doubleexchanged zeolite shouldcontain an amount of ammonium ion corresponding to at least about 5relative percent, preferably -20 percent, of the original ion exchangecapacity of the zeolite. While this remaining ion exchange capacity mayappear to represent only a small proportion of the original potentiallyactive sites, it should be emphasized that these remaining exchangesites are mostly located in the more accessible portions of the crystalstructure, and also that a large portion of catalytically activedehydroxylated exchange sites are present.

After drying at temperatures of, e.g., 212 400F, the zeolites producedas above described from highly useful dehydrating agents for gaseousmixtures, particularly gaseous mixtures which may contain ammonia orvolatile amines. They are also useful as selective adsorbents for thefractionation of a variety of hydrocarbon mixtures, as well as otherorganic compounds. They can be used to separate normal paraffins fromisoparaffins, aromatic hydrocarbons from paraffins, naph thenes fromparaffins, etc. Here again they are especially useful in adsorptionprocesses involving steam regeneration and/or in which ammonia ispresent during the adsorption or regeneration cycles.

For use as catalysts in acid catalyzed reactions such as alkylation,isomerization, cracking, hydrocracking, etc, the stabilized zeolite fromthe second ammonium ion exchange step is subjected to calcination attemperatures between about 600 and 1500F, preferably 800 1500F, for atime sufficient to effect substantial deammoniation thereof. Prior tothis calcination step, preferably following the second exchange step,the stabilized zeolite is intimately admixed with a finely dividedhydrous refractory oxide of a difficulty reducible metal. The termhydrous is used to designate oxides having structural surface hydroxylgroups detectable by infra red analysis. The preferred oxides arealumina, silica, magnesia, beryllia, zirconia, titania, thoria, chromia,and combinations thereof such as silica-alumina, silica-magnesia, andthe like. Naturally occurring clays comprising silica and alumina mayalso be utilized, preferably after acid treatment. The resultingmixtures may contain between about 0.5 and 98 weight-percent of zeolite,preferably at least about 2 weight-percent, and generally about 2 toabout 80 weight-percent, based on the combined dry weight of the zeoliteand the metal oxide. The metal oxide can be combined with the zeolite asa hydrous sol or gel, as an anhydrous activated gel, a spray driedpowder or a calcined powder. In one modification a sol or solution ofthe metal oxide precursor such as an alkali metal silicate or aluminatecan be precipitated to form a gel in the presenceof the zeolite p i Whenlesshydrous forms of the metaloxide' are combined withthe zeolite,essentially any method of effecting intimate admixture of :thecornponent s maybe uti lized. One such method is mechanical admixture,e.g., mulling, which involves admixing the zeolite in the form of apowder with the slightly hydrous, finely divided form of the metaloxide. Minoramounts of .water, with or without an acidic peptizing agentsuch as a strong mineral acid, are usually addedtofacilitate admixture.

After admixing the hydrous oxide withthe zeolite component, it isnormally preferable at'this pointto consolidate the mixture into thegranular "shapedesired for the final catalyst. Conventional tableting,prilling. or extruding procedures may be utilized to produce tablets,prills or extrudate pellets having a diameter of about 1/32 inch toinch. Other conventional pelleting aids may be added such as lubricants,binders, diluents, etc. Macro-granules of this nature are ordinarilyutilized in fixed bed processing, but other processes such as fluidcatalytic cracking require micro-granules produced for example byconventional spray drying techniques.

It is preferred to maintain a relatively anhydrous environment duringthis second calcination. If there is substantial water vapor partialpressure 2 during this step, the final catalyst is usually less activethan those produced in the substantial absence of water vapor.Accordingly, this calcination is preferably conducted in the presence ofless than 2, and preferably less than about 1, psi of water vapor. Thecalcination maybe regarded as complete when substantially all ammoniaand physically adsorbed water have been expelled from the catalyst,which, depending on the temperature employed, may range between about 10minutes and 12' hours or more. The overall severity of this calcinationshould be controlled to prevent any substantial further shrinkage in theunit cell size of the zeolite; it is essential that the final unit cellsize be above 24.40 A, preferably above about 24.44 A.

For use in hydrogenative conversion processes such as hydrocracking,hydroisomerization, etc, the necessary metal hydrogenation component maybe distributed selectively on the zeolite component of the catalyst, oron the refractory oxide component. Alternatively it may be distributedmore or less equally on both components. Effective hydrogenationcomponents comprise the Group VlB and/or Group VIII metals and theiroxides and/or sulfides, with or without other metals such as rhenium.Operative proportions (based on free metal) may range between about 0.1percent and 30 percent by weight, depending upon the type of metal ormetals selected, and the desired activity. In the case of the Group VIIInoble metals, amounts in the range of 0.1 to about 2 percent willnormally be employed; the iron group metals, iron,'cobalt and nickel,are normally utilized in proportions of about 1-10 weight-percent; theGroup VIB metals will normally be utilized in proportions of about 3-20weight-percent. Preferred hydrogenating metals are palladium, platinum,nickel, cobalt, tungsten and molybdenum. Particularly preferred arepalladium or platinum, or combinations of nickel and/or cobalt withmolybdenum and- /or tungsten.

The hydrogenating component may be added to the catalyst at any desiredstage in its manufacture. Preferred methods. include impregnation and/orionexchange of soluble metal salts into the powdered zeolite after thesecondammonium ion exchange, or into the catalyst pellets prior to thefinal calcination step. Other methods'include mixing of soluble orinsoluble compounds of the desired metal or metals with the powderedzeolite-hydrous metal oxide mixture prior to extruding or pelleting.

In addition to their low sodium content, the catalysts of this inventionare also essentially free of other zeolitic alkali and alkaline earthmetal cations, as well as rare earth metals. The presence of any ofthese zeolitic metal components in amounts exceeding about l2weight-percent is found to substantially reduce the activity of thecatalyst for acid catalyzed reactions such as cracking, hydrocracking,isomerization, etc.

The base zeolite compositions described above, or the zeolite-amorphousoxide combinations, are found to be highly active for a wide variety ofacid catalyzed hydrocarbon conversions, e.g., cracking, isomerization ofn-paraffins to isoparaffins, isomerization of alkyl aromatics,transalkylation of alkyl aromatics, alkylation, etc. For these purposes,a hydrogenation component is not ordinarily necessary, although inparaffin isomerization a hydrogenation component is sometimes desirable.For catalytic cracking, the preferred compositions comprise about 2 to25 weight-percent of the zeolite component, and 75 98 weight-percent ofthe refractory oxide component. In fluid catalytic cracking employingsuch catalyst, excellent conversions of gas oils to gasoline areobtainable under conventional cracking conditions, includingtemperatures of about 850 lOF, at 050 psig. Since catalytic crackingfeedstocks'ordinarily contain from about l02000 ppm of organic nitrogen,the ammonia-stable catalysts of this invention find particular utilityin that area.

The catalysts containing a hydrogenating component are particularlyuseful for hydrocracking. Feedstocks which may be directly subjected tohydrocracking herein include in general any mineral oil fraction boilingbetween about 200 and l400F, preferably 350 1200F. For best results thefeed should contain less than about 10 ppm, preferably less than aboutppm of organic nitrogen. The usual feedstocks include straight run gasoils, coker distillate gas oils. deasphalted crude oils, cycle oilsderived from catalytic or thermal cracking operations, and the like, anyof which may if necessary have been subjected to suitable pretreatmentto reduce the organic nitrogen content to the desired levels. Thehydrocracking can be successfully continued for periods of at leastabout 60 days in the presence of between about 5 and 5,000 ppm, but moreconventionally between about 50 2000 ppm by weight of ammonia, based onfeed. The usual products from hydrocracking include gasoline. dieselfuels, tur bine fuels, propane-butane fuels, and the like. SuitableHydrocracking Conditions Broad Range Preferred Range Temperature, F.Total Pressure, psig u-rsv H /Oil Ratio. MSCF/B At least about percentof which should be hydrogen partial pressure.

It is particularly noteworthy that the hydrocracking catalysts of thisinvention are especially useful for lowpressure hydrocracking, i.e., athydrogen pressures between about 400 and 1,000 psi. They deactivate atmuch lower rates at these low pressures than the best zeolite-basedcatalysts of the prior art.

In cases where the initial feedstock contains more than about 10 ppm oforganic nitrogen, an integral hydrofining-hydrocracking system may beutilized. In this procedure, the feedstock is first subjected to aconventional catalytic hydrofining treatment, and the effluenttherefrom, without intervening treatment to remove ammonia, is directlysubjected to the above described hydrocracking procedure.

The following examples ll5 are cited to demonstrate the superior ammoniastability and hydrothermal stability of the catalysts of this invention.

EXAMPLES l-l 2 In these examples, the starting material was asubstantially 100% crystalline ammonium Y zeolite containing about 2.4weight-percent of residual zeolitic Na O and having a unit cell size ofabout 24.703 A. Samples of this starting material were subjected to thefollowing steps in sequence:

l. An initial calcination under various conditions tabulated below;

2. Standard X ray analysis for crystallinity and unit cell size;

3. Identical ammonium ion exchange treatments with ammonium nitratesolutions to reduce the zeolitic Na O content to below about 0.3weight-percent;

4. Partial drying at l00l 10C to reduce the water content to about 25weight-percent.

5. Standard X-ray analysis for crystallinity;

6. Calcination at 900F for one hour in air;

7. Standard X-ray analysis for crystallinity (to determine hydrothermalstability);

8. Rehydration to about 20 weight-percent H O, followed by reammoniationto saturation with gaseous Nl-l at room temperature, and removal ofexcess ammonia by purging with nitrogen for 16 hours at roomtemperature;

9. Calcination at about 930F for one hour in flowing air; and

10. Standard X-ray analysis for crystallinity (to determineammonia-stability).

The results of the tests were as follows:

Table 1 Example Hrs.

lnitial Calcination H O Unit Cell psi Size. A

Temp, "F

Table 1- Continued Initial Calcination "/1 of (rystallinity Based oncrystallinity found at step (5). Based on crystallinity found at step(7). Average of 5 runs. Average of 3 runs.

The above data for crystallinity retained at step (10) (Examples l-lO)is plotted versus unit cell size in the accompanying FIG. 1, givingcurve A, which represents the percent of crystallinity which survivedthe ammonia stability test. Curve B depicts the analogous data forExamples 1 l and 12. It is evident that, for a given unit cell size, thesteam calcination of Examples llO gives products of substantiallysuperior ammonia-stability, as compared to the dry calcination ofExamples I1 and 12. The succeeding Examples 13-15 will show however thatthis desirable result is not obtained when the zeolite is essentiallyfree of sodium during the steam calcination.

The above data for crystallinity retained at step (7) (Examples l-lO) isplotted versus unit cell size in FIG. 2, giving curve D, whichrepresents the percent of crystallinity which survived the hydrothermalstability test. Curve E depicts the analogous data for Examples 11 and12. It is evident that to obtain a given degree of hydrothermalstability, considerably more unit cell shrinkage (and loss of exchangesites) is required when steam is not present during the initialcalcination.

EXAMPLES l3-l5 In these Examples the starting material was asubstantially 100% crystalline ammonium Y zeolite which had beenexhaustively ion-exchanged to a sodium content of 0.04 weight-percent asNa. Three samples of this material were subjected to the following stepsin sequence:

1. Steam calcination under conditions tabulated below;

2. Standard X-ray analysis for crystallinity and unit cell size;

3. Rehydration to about weight-percent H O, followed by reammoniation tosaturation with gaseous NH at room temperature and removal of excessammonia by purging with nitrogen for 16 hours;

4. Calcination at about 930F for one hour in flowing air; and

5. Standard X-ray analysis for crystallinity (to determineammonia-stability).

The results of the tests were as follows:

The above data for crystallinity retained at step (5) is plotted versusunit cell size in FIG. 1, giving Curve C, which represents the percentof crystallinity which survived the ammoniastability test. It is evidentthat in the absence of sodium, steam calcination is a relativelyineffective stability treatment.

The following Examples l6-28 are cited to illustrate the superiorhydrocracking activity of the catalysts of this invention, but are notto be construed as limiting in scope:

EXAMPLES l6-19 Preparation of Catalysts Catalyst A: Sodium Y zeolite wasion exchanged with ammonium sulfate solution until the'sodium contentwas reduced to 1.5 2 weight-percent N320. The resulting ammonium-sodiumzeolite was then calcined in flowing steam for one hour at 1292F andthen further ion exchanged with ammonium salt solution until the sodiumcontent was reduced to less than 0.2 percent Na O. The resulting productwas then slurried in dilute ammonium hydroxide, into which a solution ofpalladium chloride in dilute ammonium hydroxide was slowly stirred. Theproduct was washed free of chlo-- ride, mixed with 20 weight-percent(dry-basis) of acidpeptized alumina, extruded into Vs inch pellets,dried and calcined at about 900F for one hour. The finished catalystcontained about 0.5 weight-percent Pd, and the unit cell size of thezeolite was 24.483 A.

Catalyst B: A sample of Davison ultrastable zeolite Z-14US wascomposited with 0.5 weight-percent Pd and 20 percent Al O as describedabove to give a product with a unit cellsize of 24.337 A. The Z-l4USzeolite was prepared by the double-exchange, doublecalcinationprocedurev described in US. Pat. No. 2,293,192, i.e., with a firstammonium ion exchange to reduce the sodium content to about 3weight-percent Na O followed by calcination at about IOOOF, reexchangeto reduce the sodium content to below I percent Na O, and a finalcalcination at about I560F.

Catalyst C: Sodium Y zeolite was ammonium ion exchanged, steam calcinedand again ammonium ion exchanged as described in the catalyst Aprocedure.

"" Based on crystallinity found at step (2).

The resulting product was then dried and mulled with acid-peptizedalumina gel, nickel carbonate, ammonium heptamolybdate and sufficientconcentrated nickel nitrate solution to provide a moist, extrudablepaste. The proportions of ingredients were such as to provide a finishedcatalyst of about the following weight-percent composition:

Zeolite (10 A1 gel 20 M00 1 5 MO 5 EXAMPLES 23 Catalysts A, B, C and Dabove were ground to 1420 mesh particles and compared for hydrocrackingactivity, using as feedan unconverted gas oil derived from a previoushydrofining-hydrocracking run, having an AP] gravity of387, and .aboiling range of 360-870F, withabout 12 percent boiling below 400F. Fortest purposes, the feed was doped with 0.5 weight-percent sulfur asthiophene and 0.2 weight-percent nitrogen as tertbutylamine. Eachcatalyst was tested at hydrogen pressures of about 1450 and 500 psi,each run being carried out at LHSV 1.7, H /oil ratio of 8000 SCF/B, withtemperatures periodically adjusted to maintain a total liquid productgravity of 47APl. By previously established correlations, this productgravity corresponds to a conversion of about 38 volume-percent to C-400F gasoline (after deducting the 12 volumepercent of'feed whichboiled below 400F) The respective temperatures required to maintain thisconversion after 100 hours on stream were as follows:

Table 3 Catalyst 7 Temperatures for 38% Conversion, "F

1450 psi 500 psi A 689 736 B 7l2 742 C 707 724 D 722 840 "Catalyst wasdeactivating so rapidly that only about 23 percent conversion was beingobtained. TIR was about 22F per day with no apparent leveling out.

Since a reduction of about 20F in temperature required to maintainconversion corresponds to about doubling the catalyst activity (on acatalyst volume basis), it will be apparent that catalysts A and C ofthis invention were substantially superior to catalysts B and D of theprior art. Catalyst C was particularly outstanding at 500 psi, whilecatalyst A was particularly outstanding at 1450 psi (the TIR notationabove refers to the average daily temperature increase required formaintaining the stated conversion level.)

EXAMPLES 24-26 Catalysts A, B and D were tested as described in Ex-Table 4 Catalyst Temperature for 48% Conversion, F

A 510 B 538 D 550 lt will be seen that at 1450 psi, catalyst A wassubstantially superior to either of the prior art catalysts B or D.

EXAMPLE 27 Catalyst C was used to hydrocrack another hydrofined gas oilhaving an API gravity of 35 and a boiling range of 1757l6F, with about9% boiling below 400F. The feed contained about 1 ppm nitrogen and 12ppm sulfur.

The catalyst was presulfided with a H /H S mixture and evaluated at 950psig, and at 3.0 and 1.7 LHSV. H loil ratio was 8000 SCF/B. Thetemperature was periodically adjusted to maintain a total productgravity of 60.5APl, corresponding to a conversion of about volumepercent per pass to C -40OF gasoline (after deducting the 9volume-percent of feed boiling below After 250 hours on stream at 3.0LHSV, the temperature required to maintain conversion was about 660F andthe deactivation rate was about 2.5F per day. After 300 hours on streamthe deactivation rate was about 1.2F per day. After a further 160 hourson stream at 1.7 LHSV the deactivation rate was less than 03F per day,and the temperature required to maintain 80% conversion to 400F endpoint gasoline was 642F.

From this data, it can be deduced that a commercial operation of greaterthan six months duration is feasible using the above conditions.

EXAMPLE 28 Operation as in Example 27 was continued at 700 psig and 1.7LHSV. After a further hours on stream, the required temperature for 80%conversion was 670F, and the deactivation rate was less than 0.5F perday.

Examples 24-28 demonstrate that, even in the absence of ammonia. thecatalysts of this invention are substantially more active than the priorart catalysts.

The following claims and their obvious equivalents are intended todefine the true scope of the invention:

1 claim: 1

l. A process for the hydrocracking of a hydrocarbon feedstock to producea lower boiling hydrocarbon product, which comprises subjecting saidfeedstock plus added hydrogen to hydrocracking conditions of pressureand temperature in contact with a catalyst comprising a Group /lB and/orGroup. Vlll, metal, metal oxide or metal sulfide hydrogenatingcomponentintimately dispersed in a stabilized metal-cationdeficient Y Zeolitecracking base, said cracking base having been prepared by the steps of:

l. calcining an ammonium-sodium Y zeolite containing about 0.6weight-percent of sodium as Na O, said calcining being carried out at atemperature between about 600and 1650F in contact with at least about0.2 psi of water vapor for a sufficient time to substantially reduce theunit cell size of said zeolite and bring it to a value between about24.40 and 24.64 A;

2. subjecting the calcined zeolite to further ammonium ion exchangeunder conditions adjusted to replace at least about 25 percent of itsresidual zeolitic sodium ions with ammonium ions and produce a finalproduct containing less than about 1 weightpercent Na O;

3. consolidating the product from step (2) into granules havingintimately admixed therein a finely divided hydrous oxide selected fromthe class consisting of alumina, silica, magnesia, titania, zirco nia,thoria, beryllia, chromia, clays and mixtures thereof; and

4. calcining the granules at a temperature between about 600 and l500Ffor a time sufficient to effect substantial deammoniation, butinsufficient to reduce the unit cell size of the zeolite to below about24.40 A.

2. A process as defined in claim 1 wherein said hydrogenating componentis palladium and/or platinum.

3. A process as defined in claim 1 wherein said hydrogenating componentcomprises nickel and molybdenum as free metals, oxides or sulfides.

4. A process as defined in claim 1 wherein said feedstock is a mineraloil fraction boiling predominantly above 400F, and said hydrocarbonproduct comprises gasoline and/or turbine fuel and/or diesel fuel.

5. A process as defined in claim 1 wherein step (4) is carried out undersubstantially dry conditions.

6. A process as defined in claim 1 wherein said hydrous oxide isessentially alumina.

7. A process as defined in claim 6 wherein said hydrogenating componentis palladium and/or platinum.

8. A process as defined in claim 6 wherein said hydrogenating componentcomprises nickel and molybdenum as free metals, oxides or sulfides.

9. A process for the hydrocracking of a hydrocarbon feedstock to producea lower boiling hydrocarbon product, which comprises subjecting saidfeedstock plus added hydrogen to hydrocracking conditions of pressureand temperature in contact with a catalyst comprising a Group VIB and/orGroup VIII metal,

metal oxide or metal sulfide hydrogenating component intimatelydispersed in a stabilized metal-cationdeficient Y zeolite cracking base.said cracking base having been prepared by the steps of:

1. calcining an ammonium-sodium Y zeolite containing about 1 4 weightpercent of sodium as Na O, said calcining being carried out at atemperature between about 800 and l650F in contact with between about2-l 5 psi of water vapor for a sufficient time to substantially reducethe unit cell size of said zeolite and bring it to a value between about24.42 and 24.62 A.;

2. subjecting the calcined zeolite to further ammonium ion exchangeunder conditions adjusted to replace at least about percent of itsresidual zeolitic sodium ions with ammonium ions and produce a finalproduct containing less than about 0.6 weight-percent Na O;

3. consolidating the product from step (2) into granules havingintimately admixed therein a finely divided hydrous oxide selected fromthe class consisting of alumina, silica, magnesia, titania, zirconia,thoria, beryllia, chromia, clays and mixtures thereof; and

4. calcining the granules at a temperature between about 800 and l500Ffor a time sufficient to effect substantial deammoniation, butinsufficient to reduce the unit cell size of the zeolite to below about24.40 A.

10. A process as defined in claim 9 wherein said hydrogenating componentis palladium and/or platinum.

11. A process as defined in claim 9 wherein said hydrogenating componentcomprises nickel and molybdenum as free metals, oxides or sulfides.

12. A process as defined in claim 9 wherein said feedstock is a mineraloil fraction boiling predominantly above 400F, and said hydrocarbonproduct comprises gasoline and/or turbine fuel and/or diesel fuel.

13. A process as defined in claim 9 wherein step (4) is carried outunder substantially dry conditions.

14. A process as defined in claim 9 wherein said hydrous oxide isessentially alumina.

15. A process as defined in claim 14 wherein said hydrogenatingcomponent is palladium and/or platinum.

16. A process as defined in claim 14 wherein said hydrogenatingcomponent comprises nickel and molybdenum as free metals, oxides orsulfides.

1. CALCINING AN AMMONIUM-SODIUM Y ZEOLITE CONTAINING ABOUT 0.6 - 5WEIGHT-PERCENT OF SODIUM AS NA2O, SAID CALCINING BEING CARRIED OUT AT ATEMPERATURE BETWEEN ABOUT 600* AND 1650*F IN CONTACT WITH AT LEAST ABOUT00.2 PSI OF WATER VAPOR FOR A SUFFICIENT TIME TO SUBSTANTIALLY REDUCETHE UNIT CELL ZSIZE OF SAID ZEOLITE AND BRING IT TO A VALUE BETWEENABOUT 24.40 AND 24.64 A,
 1. A PROCESS FOR THE HYDROCRACKING OF AHYDROCARBON FEEDSTOCK TO PRODUCE A LOWER BOILING HYDROCARBON PRODUCE,WHICH COMPRISES SUBJECTING SAID FEEDSTOCK PLUS ADDED HYDROGEN TOHYDROCRACKING CONDITIONS OF PRESSURE AND TEMPERATURE IN CONTACT WITH ACATALYST COMPRISING A GROUP VIB AND/OR GROUP VIII METAL, METAL OXIDE ORMETAL SULFIDE HYDROGENATING COMPONENT INTIMATELY DISPERSED IN ASTABILIZED METAL-CATION-DEFICIENT Y ZEOLITE CRACKING BASE, SAID CRACKINGBASE HAVING BEEN PREPARED BY THE STEPS OF:
 2. A process as defined inclaim 1 wherein said hydrogenating component is palladium and/orplatinum.
 2. subjecting the calcined zeolite to further ammonium ionexchange under conditions adjusted to replace at least about 25 percentof its residual zeolitic sodium ions with ammonium ions and produce afinal product containing less than about 1 weight-percent Na2O; 2.SUBJECTING THE CALCINED ZEOLITE TO FURTHER AMMONIUM ION EXCHANGE UNDERCONDITIONS ADJUSTED TO REPLACE AT LEAST ABOUT 25 PERCENT OF ITS RESIDUALZEOLITIC SODIUM IONS WITH AMMONIUM IONS AND PRODUCE A FINAL PRODUCECONTAINING LESS THAN ABOUT 1 WEIGHT-PERCENT NA2O,
 2. subjecting thecalcined zeolite to further ammonium ion exchange under conditionsadjusted to replace at least about 70 percent of its residual zeoliticsodium ions with ammonium ions and produce a final product containingless than about 0.6 weight-percent Na2O;
 3. consolidating the productfrom step (2) into granules having intimately admixed therein a finelydivided hydrous oxide selected from the class consisting of alumina,silica, magnesia, titania, zirconia, thoria, beryllia, chromia, claysand mixtures thereof; and
 3. CONSOLIDATING THE PRODUCT FROM STEP (2)INTO GRANULES HAVING INTIMATELY ASMIXED THEREIN A FINELY DIVIDED HYDROUSOXIDE SELECTED FROM THE CLASS CONSISTING OF ALUMINA, SILICA, MAGNESIA,TITANIA, ZIRCONIA, THORIA, BERYLLIA, CHROMIA, CLAYS AND MIXTURESTHEREOF, AND
 3. A process as defined in claim 1 wherein saidhydrogenating component comprises nickel and molybdenum as free metals,oxides or sulfides.
 3. consolidating the product from step (2) intogranules having intimately admixed therein a finely divided hydrousoxide selected from the class consisting of alumina, silica, magnesia,titania, zirconia, thoria, beryllia, chromia, clays and mixturesthereof; and
 4. calcining the granules at a temperature between about600* and 1500*F for a time sufficient to effect substantialdeammoniation, but insufficient to reduce the unit cell size of thezeolite to below about 24.40 A.
 4. CALCINING THE GRANULES AT ATEMPERATURE BETWEEN ABOUT 600* AND 1500*F FOR A TIME SUFFICIENT TOEFFECT SUBSTANTIAL DEAMMONIATION, BUT INSUFFICIENT TO REDUCE THE UNITCELL SIZE OF THE ZEOLITE TO BELOW ABOUT 24.40 A.
 4. A process as definedin claim 1 wherein said feedstock is a mineral oil fraction boilingpredominantly above 400*F, and said hydrocarbon product comprisesgasoline and/or turbine fuel and/or diesel fuel.
 4. calcining thegranules at a temperature between about 800* and 1500*F for a timesufficient to effect substantial deammoniation, but insufficient toreduce the unit cell size of the zeolite to below about 24.40 A.
 5. Aprocess as defined in claim 1 wherein step (4) is carried out undersubstantially dry conditions.
 6. A process as defined in claim 1 whereinsaid hydrous oxide is essentially alumina.
 7. A process as defined inclaim 6 wherein said hydrogenating component is palladium and/orplatinum.
 8. A process as defined in claim 6 wherein said hydrogenatingcomponent comprises nickel and molybdenum as free metals, oxides orsulfides.
 9. A process for the hydrocracking of a hydrocarbon feedstockto produce a lower boiling hydrocarbon product, which comprisessubjecting said feedstock plus added hydrogen to hydrocrackingconditions of pressure and temPerature in contact with a catalystcomprising a Group VIB and/or Group VIII metal, metal oxide or metalsulfide hydrogenating component intimately dispersed in a stabilizedmetal-cation-deficient Y zeolite cracking base, said cracking basehaving been prepared by the steps of:
 10. A process as defined in claim9 wherein said hydrogenating component is palladium and/or platinum. 11.A process as defined in claim 9 wherein said hydrogenating componentcomprises nickel and molybdenum as free metals, oxides or sulfides. 12.A process as defined in claim 9 wherein said feedstock is a mineral oilfraction boiling predominantly above 400*F, and said hydrocarbon productcomprises gasoline and/or turbine fuel and/or diesel fuel.
 13. A processas defined in claim 9 wherein step (4) is carried out undersubstantially dry conditions.
 14. A process as defined in claim 9wherein said hydrous oxide is essentially alumina.
 15. A process asdefined in claim 14 wherein said hydrogenating component is palladiumand/or platinum.
 16. A process as defined in claim 14 wherein saidhydrogenating component comprises nickel and molybdenum as free metals,oxides or sulfides.